1. Field
The invention is in the field of communication systems, and more particularly communications systems for use in teleconferencing and teaching presentations which utilize supporting materials which can be prepared ahead of the presentation.
2. State of the Art
Most classroom and other presentations to groups are made by a speaker actually being present before the group to give the presentation and in many cases to present supporting material for the presentation. The supporting material may be visual material such as slides, movies, or video material, computer demonstrations, or even high fidelity audio material. When groups desire to have a presentation made by a person who lives in an area remote from where the presentation is to be made, it becomes expensive to transport the person to the location of the presentation and, in many instances, to provide lodging for the person. Many groups would like to have various speakers but because of the costs involved, cannot afford to do so. Further, many professors would like to have guest lecturers for their classes, but again, because of cost, cannot afford to bring in the guest lecturers.
While speakers phones exist and a presentation to a group can be made by telephone, such procedure does not allow use by the speaker of supporting material to illustrate or otherwise support the presentation and has not been accepted as a viable substitute for a live presentation.
Video tape presentations are not the equivalent of live presentations and allow no audience participation. Live presentations utilizing television transmissions, closed circuit or otherwise, require special studios and expensive transmitting and receiving equipment.
Providing visual as well as audio information live at remote locations in a manner similar to providing audio information by means of a telephone has been desireable since the development of telecommunications. As technology advanced, various forms of video transmission for teleconferencing have developed utilizing microwave links, satellite transmission, and more recently, specialized wide band digital telephone lines which allow digitized images, both still and moving, to be transmitted and received on appropriate equipment. Such systems are described in "Picture Phones Get a New Image", by Wesley R. Iversen in "Electronics", Aug. 19, 1985. The major stumbling block to live video transmission for teleconferencing is the fact that even with innovative signal processing, the large amount of information which must be transmitted for visual images has always precluded the use of standard "voice grade" telephone lines for satisfactory picture transmission, since the bandwidth of these lines is severely limited. This, in turn, has prevented the development of a widespread video network for teleconferencing using telephone lines as the present world telephone system is not able to provide the necessary wide band links from all possible sending location to all possible receiving locations, nor does it appear that this will be the case in the foreseeable future. In order to provide viable visual teleconferencing using the existing world telephone system, a means is needed whereby a high quality visual presentation may be made over existing telephone lines.